<!DOCTYPE html>
<html lang="zh">
  <head>
    <meta charset="utf-8">
    <link rel="stylesheet" href="style.css">
    <title>12 新拟态输入框</title>
  </head>
  <style>
	  .app{
	    width: 100%;
	    height: 100vh;
	    background-color: #e0e0e0;
	    position: relative;
	    display: flex;
	    justify-content: center;
	    align-items: center;
	  }
	  input {
	    width: 180px;
	    height: 56px;
	    border: none;
	    outline-style: none;
	    font-size: 16px;
	    color: #333333;
	    padding: 0 28px;
	    border-radius: 28px;
	    background: #e0e0e0;
	    box-shadow: 6px 6px 12px #b8b8b8, -6px -6px 12px #ffffff, inset 0 0 0 #b8b8b8, inset 0 0 0 #ffffff;
	    transition: all .24s ease-in-out;
	  }
	  input:focus{
	    box-shadow: 0 0 0 #b8b8b8, 0 0 0 #ffffff, inset 6px 6px 12px #b8b8b8, inset -6px -6px 12px #ffffff;
	  }
	  input::placeholder {
	    color: rgba(0, 0, 0, 0.4);
	    font-size: 16px;
	    font-weight: 700;
	    transition: all .24s ease-in-out;
	  }
	  input:focus::placeholder {
	    color: rgba(0, 0, 0, 0.8);
	  }
  </style>
  <body>
    <div class="app">
      <input type="text" placeholder="用户名/邮箱">
    </div>
  </body>
</html>